Open AccessIdentification of cytochrome c oxidase in the alkaliphilic, obligately chemolithoautotrophic, sulfur‐oxidizing bacterium ‘ Thioalcalomicrobium aerophilum ’ strain AL 3
Author(s) -
Sorokin Dimitry Yu.,
Cherepanov Alexei,
Vries Simon,
Kuenen Gijs J.
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb08713.x
Subject(s) - cytochrome , cytochrome c oxidase , biochemistry , bacteria , oxidase test , chemistry , cytochrome c , heme , enzyme , biology , mitochondrion , genetics
Cytochrome c oxidase from the novel alkaliphilic autotrophic sulfur bacterium ‘ Thioalcalomicrobium aerophilum ’ strain AL 3 was isolated and purified 87‐fold. Spectroscopic analysis revealed the presence of both c ‐ and b ‐type hemes as well as copper in a ratio of 3:2:1. The purified enzyme consists of three subunits with apparent molecular masses of 41, 34 and 32 kDa. The two small subunits contain covalently bound heme c . With TMPD as a substrate the pH optimum was determined to be pH 8.0. In the presence of monovalent cations the specific activity of the purified oxidase increased significantly. The enzyme was not able to oxidize external cytochrome c , but accepted electron from its native electron donor. The latter was separated from the other membrane cytochromes during anion‐exchange chromatography and was identified as a high potential cytochrome c 551 . Overall the data indicate that the cytochrome c oxidase from this alkaliphilic autotrophic bacterium belongs to the heme‐copper oxidase superfamily; regarding its subunit composition and content of prosthetic groups, the enzyme is similar in many aspects to the cbb 3 ‐type cytochrome c oxidases described for several neutrophilic bacteria, including anaerobic phototrophic and aerobic sulfur‐oxidizing bacteria.